1. Field of the Invention
The present invention relates to a communications system and a communications method for transmitting data including, as a destination address, a second terminal ID (information identifying the second terminal), from a first terminal to the second terminal via a plurality of transfer devices, and a transfer device and a network manager suitable for use therein.
2. Description of the Related Art
In a conventional communications system, a terminal moving within a communications network uses address information assigned by an access network with which the terminal has newly established connection at a new location, for communications. A given address information piece is assigned to the terminal from among address information pieces assigned to an access network to which the terminal is physically connected.
The conventional communications system, however, has a problem in that when the terminal conducts communications using the assigned address information, the party on the other end of the connection can detect from the address information the access network to which the above terminal is physically connected. That is, in such a case, the location information of the user can be problematically leaked to the party on the other end.
As an art designed to provide packet transmitting and receiving functions to a terminal moving within a communications network under the same setting environment, “Mobile IP” is known.
Under “Mobile IP,” in order to prevent the leakage of the location information of the user, the terminal always transmits to the party on the other end, data with a “home address” assigned by a “home agent” of a “home network” set as the source address. The party on the other end always transmits data provided with the “home address” to the terminal, assuming that the terminal is located in the “home network.” As a result, the data transmitted from the party on the other end is always transferred to the “home network (home agent)” of the terminal and then transferred from the “home network” to a network to which the terminal is connected at that time.
The conventional communications system using “Mobile IP,” however, has a problem in that the terminal needs to perform complicated settings so as to specify information for transfer to the terminal, for the “home agent.”
The conventional communications system using “Mobile IP” has another problem in view of a data transfer path in which data transferred must pass through a relay point (home agent) constituting a triangular path.
The conventional communications system using “Mobile IP” has yet another problem in that the terminal needs to perform highly functional processing. The terminal needs, for example, to hold both the address information assigned by an access network to which the terminal is connected, and the home address of the terminal, and to perform such processing as releasing the encapsulation of packets received.
The conventional communications system using “Mobile IP” has still another problem in that it is required to transmit and receive packets in a format which includes an information element constituting an overhead, even in a radio section between the terminal and an access point in the access network.
The conventional communications system using “Mobile IP” has still another problem in that it is based on “end-to-end data transfer”, a basic principle of the internet protocol, and the terminal needs to specify, as transfer information, both a terminal ID and routing information (that is, address information assigned by an access network and a terminal home address) for data transfer.
The conventional communications system using “Mobile IP” has still another problem in that path-to-path processing, routing processing, or the like, results in a transmission mode including redundant path information.
The conventional communications system using “Mobile IP” has still another problem in that since bandwidth control is performed by encapsulation using MPLS or the like, the party on the other end can detect the location information of the terminal from address information assigned by an access network.